HD 2421

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HD 2421
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Andromeda
Right ascension 0h 28m 13.655s[1]
Declination +44° 23′ 40.03″[1]
Apparent magnitude (V) 5.18
Spectral type A2V[2]/F2V[3]
Proper motion (μ) RA: 85.12±0.17[1] mas/yr
Dec.: −14.90±0.16[1] mas/yr
Parallax (π)11.54 ± 0.28[1] mas
Distance283 ± 7 ly
(87 ± 2 pc)
PrimaryHD 2421A
CompanionHD 2421B
Period (P)3.95529±0.00003 d
Eccentricity (e)0.135±0.011
Periastron epoch (T)2448523.14±0.04
Argument of periastron (ω)
Argument of periastron (ω)
Semi-amplitude (K1)
49.1±0.6 km/s
Semi-amplitude (K2)
81.1±1.0 km/s
Other designations
BD+43° 92, HD 2421, HIP 2225, HR 104, SAO 36390[5]
Database references

HD 2421 is a spectroscopic binary with a class A main-sequence primary and a class F main-sequence secondary[3] in the constellation Andromeda. Its apparent magnitude is 5.18 and it is approximately 283 light years away based on parallax.

Binary system[edit]

The binary has a period of 3.96 days and a eccentricity of 0.135. The variable radial velocity was first reported by Robert Horace Baker in 1909 and the first orbit computed by Stella Udick in 1912.[6] A refined orbit was published in 1993 resulting in updated orbital parameters.[4]


  1. ^ a b c d e van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.Vizier catalog entry
  2. ^ Cowley, A.; et al. (1969). "A study of the bright stars. I. A catalogue of spectral classifications". The Astronomical Journal. 74: 375–406. Bibcode:1969AJ.....74..375C. doi:10.1086/110819.
  3. ^ a b Adelman, Saul J.; et al. (2015). "Elemental Abundance Analyses with DAO Spectrograms. XXXVIII. The SB2 Stars HR 104 (A2 V) and θ Aql (B9.5 III)". Publications of the Astronomical Society of the Pacific. 127 (952): 509–515. Bibcode:2015PASP..127..509A. doi:10.1086/682075.
  4. ^ a b Hill, Graham; et al. (1993). "The double-lined spectroscopic binary HR 104". Publications of the Astronomical Society of the Pacific. 105: 748–750. Bibcode:1993PASP..105..748H. doi:10.1086/133225.
  5. ^ "HD 2421". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-03-03.
  6. ^ Udick, Stella (1912). "The orbit of B. D. + 43° 92". Publications of the Allegheny Observatory of the University of Pittsburgh. 2 (18): 191–196. Bibcode:1912PAllO...2..191U.